I think I've found a contender.
Now if you're easily disturbed I'd tell you not to read on... it's 3am and it's probably not a good idea I'm doing this exactly, but I'm sure someone may be interested...
DO NOT click if you think you're prone to being disturbed:
http://uk.youtube.com/watch?v=EXg2HGFLLIc
Stalaggh, I've been told, are composed of artists, black metal musicians and noise musicians. One member is an insane guy who killed his own mother at 16. One of the "musicians" was almost murdered during the recording process and it was all recorded.
The video itself is recorded with WWII mental patients screaming footage with someone's manipulated screaming above it. The rest I'll leave to you.